1. Field of the Invention
The present invention relates to an ignition device and more particularly to an ignition device for an internal combustion engine of a vehicle, etc.
2. Discussion of the Background
In general, a single ignition coil of a normal engine is located on the engine for an ignition spark plug, and the single ignition coil is connected to all of the ignition spark plugs by a high-tension wire. It is also known to locate an ignition coil at each portion of the engine where each ignition spark plug is fixed to the engine and to directly connect each ignition coil with its respective ignition spark plug, since electrical loss is very large in the high-tension wire.
A conventional ignition device related to the present invention is disclosed in Japanese Utility Model Laid-open No. 63-67646 published on May 5, 1988, and is shown in FIG. 5. There, an engine 71 has plural cylinders (not shown). Each cylinder is formed in a cylinder block having a head 72 which is covered with a cylinder head-cover 73. The engine has two cam-shafts 74 and cam-shafts stoppers 75. The number of ignition spark plugs 76 and the number of ignition coils 77 are the same as the number of the cylinders. Each ignition spark plug 76 is fixed to the cylinder head 72 in the corresponding plug hole 78. Respective plural sleeves 79 are fixed to the corresponding plug holes 78. Each ignition coil 77 is held between the cylinder headcover 73 and the corresponding sleeve 79 via a gasket 80.
The above-mentioned ignition device has several disadvantages. Namely, if a disconnection of the ignition coil 77 or a damage of the ignition spark plug 76 occurs, the cylinder head-cover 73 must be removed for repairing the ignition coil 77 or the ignition spark plugs 76. This is very cumbersome work and repetition of such work damages the gasket 80. Thus, the sealing function of the gasket 80 is impaired, so that lubricating oil for the engine 71 leaks through the gasket 80 and causes malfunctions.